1. Field of the Invention
The present invention relates to a vehicular lamp. More particularly, the present invention relates to a vehicular lamp used for a vehicle.
2. Description of the Related Art
A vehicular lamp using a filament bulb as a light source has been known so far. In this lamp the open circuit of the light source is detected by measuring the impedance of the lamp. In addition, a vehicular lamp open circuit detecting apparatus used for a brake lamp with multiple lamp units has been known as disclosed, for example, in Japanese Patent Application Laid-Open No. 1998-217851.
If a light emitting diode is used as the light source, however, the light emitting diode causes a forward voltage higher than that of the lamp filament. Accordingly, the impedance of the lamp reaches a high level even though the light emitting diode as a light source is not open-circuited. Therefore, it might be difficult to properly detect the open circuit of the light source.